Flattening backs; 100 grit?

[Moses Yoder]

Okay, honesty; a small portion of this post is simply to gloat about the box full of Buck Bro's chisels I bought for $25. Really though, I want to flatten the backs. I have a piece of 1/2" glass and plan on getting 100 grit silicon carbide sheets from Klingspors for the initial flattening. After they are flat I plan on polishing them with my 1000, 4000, and 8000 grit water stones. Does this sound like a reasonable plan? In the past I have found the water stones tend to conform to the iron, they wear so fast. The chisels look like the started with a set of 4 that are 1/4", 1/2", 3/4" and 1". Later a 1-1/4" chisel was added, I am not sure it is a Buck Bros. , and then a 1-1/2" & 2" were added. I bought the set for $25 at a local community garage sale. Thanks for any advice on flattening the backs.

Chisels Buck Bros.jpg

[Jessica Pierce-LaRose]

I'm interested in hearing comments on this from folks like David. I have mixed results with sandpaper lapping - sometimes it's a god send, sometimes due ot some user error I can't identify I get some very annoying dubbing that's a pain to work out. I recently picked up one of the steel lapping plates from LV, and am figuring on trying loose grit on the plate (should I try and track down some PSA plastic like LV sells for their glass-lapping kit?) for my next major rehab attempt.

I will say that I like to start with something milder than 100 grit w/d - I often start on my freshly flattened 1000 grit waterstone - it's nice to get a sense of how out-of-whack it is from something a little less aggressive - sometimes an old tool can surprise you (hopefully pleasantly, like a tool that's got a bit of a hollow in it) and you can tackle the whole job there without making more work for yourself with scratches that need to be taken out by moving up in grits, other times it can help you identify quickly that there's a low corner or backbevel and the better approach might be just to move to grinder to move the bevel back by a hair than waste a lot of time flattening to get one low spot in check.

As I start to care more about my time than how purty my tools look, I've taken to more frequently going at the less-important parts of the back with a small grinding stone, as Garrett Hack mentions in his Hand Tools book, something I've mentioned before, to add a poor-mans hollow to the back of my blades and speed up the lapping process by having to lap less metal. It also makes things much easier if you stumble across an otherwise-great blade that rocks a bit due to convexity. I go back and forth between lapping and grinding to avoid to overdoing things, and to keep an eye what's happening. You can figure out a lot of the topography of the blade by looking at the scratch pattern.

Either way, that's a very nice set of chisels! I really like having a nice, wide chisel at hand - that two incher should be nice. They look well-cared for - have you touched the backs yet? They might surprise you. For me, just having stumbling across something that still has a handle and hasn't obviously been used to open paint cans is a good find .. .

[David Weaver]

100 grit 3x, stuck down *hard and fast* with spray adhesive so it doesn't move or creep at all. If you use spray adhesive, let it dry before you use it.

Silicon carbide breaks down too easily, which might not be a big deal if those chisels are soft and/or already close to flat.

If the paper isn't stuck down hard and fast to start with, it will just dub around all of the edges of the chisels making for a very unhappy conclusion when you go to the next grit.

PSA 80 grit aluminum oxide rolls from someone like mirka are also good (they stick down hard and fast, though they're not cheap - but then again, neither is norton 3x in any quantity).

[Tom M King]

I start with 400 to just see what it looks like before going coarser-same with plane soles. No need to make more scratches than you have to. I use the best quality 3M wet-or-dry paper-not the stuff you buy in a hardware or auto parts store. The stuff that costs 4 to 7 bucks a sheet lasts many times longer.

I use it on a granite surface plate (Woodcraft has them on sale now http://www.woodcraft.com/product/200...2-a-grade.aspx ) with nothing holding them in place other than a splash of water under it. That doesn't work on anything else that I know of, but the surface texture on the granite surface plate lets it happen. For the finer grits, you sometimes have to lay a strip of something on each side to keep the edges from curling up.

Cheap paper is a waste of money. I use the same setup for flattening Norton water stones, and one sheet of 100 lasts me many flattenings. I just leave it on the sink, and rinse it when I'm done. It'll be dry and ready to go the next time.

Here's a link to the high-dollar wet-or-dry. It puts wet-or-dry sandpaper in a different category than what most people are used to. http://www.multitechproducts.com/100...dry-sandpaper/

The granite surface plate is worth the 25 bucks just to not have to deal with glueing the paper down. To change grits, you pull one up, and slap on the next.

[bridger berdel]

I also jump back and forth between a grinder and a lap to speed things up. for the lap I often use a diamond hone, for the grinder I have a cheap angle die grinder fitted up with small sanding disks. makes it easy to see the scratch pattern from the lap because you are working the chisel belly up and the small area of the disk allows pretty good control over what metal is being ground away.